<template>
  <div class="spec-preview">
    <img :src="skuImageList[imgIndex].imgUrl" />
    <!-- 移动放大镜 -->
    <div class="event" @mousemove="handler"></div>
    <div class="big">
      <img :src="skuImageList[imgIndex].imgUrl" ref="big"/>
    </div>
    <!-- 遮罩层 -->
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  props:['skuImageList'],
  data() {
    return {
      imgIndex:0
    }
  },
  mounted() {
    // 兄弟组件间通信：全局事件总线
    this.$bus.$on('showBigImage',(index)=>{
      this.imgIndex=index
    })
  },
  methods: {
    handler(e){
      let mask=this.$refs['mask']
      // console.log(e); 这里的event是鼠标移动事件 
      // console.log(mask.offsetWidth); mask是div元素，它有css属性
      let left=e.offsetX-mask.offsetWidth/2
      let top=e.offsetY-mask.offsetHeight/2
      if(left<0){
        left=0
      }else if(left>mask.offsetWidth){
        left=mask.offsetWidth
      }
      if(top<0){
        top=0
      }else if(top>mask.offsetHeight){
        top=mask.offsetHeight
      }
      mask.style.left=left+'px'
      mask.style.top=top+'px'

      let big=this.$refs['big']
      big.style.left=-2*left+'px'
      big.style.top=-2*top+'px'
    }
  },
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>